1. Field of the Invention
The present invention relates to a support apparatus for a utility access cover and, in particular, to a support apparatus for adjusting the elevation and gradient of a utility access opening.
2. Description of the Related Art
It is known to use either a brick or concrete riser ring structure to adjust the height and inclination of a utility access opening. This is a difficult and time consuming process when the utility access opening must be set substantially coplanar with an existing or proposed surrounding surface. When done conventionally it is necessary preferable to mortar all horizontal and vertical joint surfaces and ensure that there are no voids in the mortar. However, often foreign objects such as small rocks or pieces of wood are instead used as wedges to set the elevation and gradient of the access opening. Mortar is then simply applied to the interior and exterior side walls of the brick or concrete riser ring structure. This leaves voids in the brick or concrete riser ring structure and compromises the integrity of the structure.
It is also known to use a prefabricated support structure to adjust the height and inclination of a utility access opening. The height and inclination of the utility access opening is adjusted by setting the base of the support structure to a desired elevation and gradient. Since all adjustments are made at the base of the support structure it can be difficult to achieve the height and inclination required so the utility access opening is substantially coplanar with an existing or proposed surrounding surface. It is often necessary to remove backfill to reset the base of the support structure which is both costly and time consuming. To overcome the aforementioned difficulties numerous adjustable support structures have been developed for adjusting the height and inclination of a utility access opening.
U.S. Pat. No. 4,038,789 issued on Aug. 2, 1977 to Axegärde et al., and the full disclosure of which is incorporated herein by reference, discloses an adjustable manhole assembly comprising a top frame for carrying a cover and a bottom frame supported on a base for the manhole. A portion of the top frame is telescoped in the bottom frame. There is a plurality of lock means for locking the frames in a mutually-adjusted position. The lock means extend between the portion of the top frame inserted in the bottom frame and include laterally projecting screws terminating outside of the portion telescoped in the bottom frame. The bottom frame includes counterpressure surfaces confrontingly disposed adjacent the ends of the screws for engagement therewith when the screws are tightened. The counterpressure surfaces extend at a vertical angle with respect to the vertical axis of the bottom frame and converge downwardly. The protruding screws have a plurality of adjusted positions along the angular counterpressure surface to position the frames at different adjusted levels. The longitudinal axes of said screws are substantially perpendicular to a corresponding counterpressure surface with which it cooperates, and the end portions of the screws move substantially parallel against the counterpressure surface when the screws are tightened.
U.S. Pat. No. 5,165,819 issued on Nov. 4, 1992 to Bowman, and full disclosure of which is incorporated herein by reference, discloses a manhole cover support which may be held level or at an incline while still permitting the efficient establishment of a new cover height elevation and adjustment of the same. The cover support is adaptable to standardize on the manhole cover size and inventory of covers for a group of manhole installations having geometrically similar but somewhat varying sizes. The cover support comprises a top peripheral flange having a seat for a manhole cover and a cover keeper that rises from the outer periphery of the seat. There is a base fitting into the confines of the cover keeper of an existing manhole cover-receiving structure such as a manhole frame. The base supports the flange and is in a slidable engagement with the flange.
U.S. Pat. No. 5,513,926 issued on May 7, 1996 to Prescott, and the full disclosure of which is incorporated herein by reference, discloses an adjustable manhole head assembly for mounting a cover onto a manhole frame. The assembly has a lower annular rim member and an upper annular rim member. The lower member has a bottom side which is sized and shaped to rest on the manhole frame. The lower member also has an opposite top side with an inner surface portion which is sized and shaped to receive and support the peripheral bottom portion of the cover. The opposite top side of the lower member also has an outer surface portion. The upper annular rim member has a bottom side sized and shaped to rest onto the outer surface portion of the top side of the lower rim member in order to fully surround the peripheral edge of the cover when the upper annular rim member lays on the inner surface portion of the top side of the lower rim member. The upper annular rim member also has an opposite top side and a thickness substantially equal to one of the peripheral sidewalls of the cover. Bolts are used for anchoring to the manhole frame together with the upper and lower rim members in an operative position to receive and support the cover. The manhole head assembly can be vertically adjusted with one or more intermediate rim members to conform to new surrounding surface levels.
U.S. Pat. No. 5,934,820 issued on Aug. 10, 1999 to Hinkle, and the full disclosure of which is incorporated herein by reference, discloses a system and method for raising a manhole ring during construction of roads. The system includes a generally tubular form for placing on a manhole cone in an excavation, and a trimming/cutting tool for adjusting the height of the form. The cutting tool is preferably positioned inside the form and is rotated around to cut a ring of material off of the top of the form. The cutting tool is set at a desired elevation, indexed off of the pavement around the excavation, which results in the form being cut to a height that can support a manhole ring at a proper elevation to be flush with the pavement surface of a particular site. A single pour of concrete may be done to create a concrete collar that fills and seals the vertical space between the manhole cone and ring. The form may include a stabilizing system for holding the form in place on the manhole cone.
U.S. Pat. No. 6,524,026 issued on Feb. 25, 2003 to Sondrup, and the full disclosure of which is incorporated herein, discloses a height adjustable utility access device, such as a manhole, which adjusts in height to allow a top of a cover to sit flush with the surrounding surface, such as a road. The device has a cover which covers access to the utility; a frame coupled over the utility; and an adjuster, coupled between the cover and the frame, for adjusting the height of the cover relative to the frame. The adjuster can include an adaptor ring on the frame and an extension ring on the adaptor ring. The extension ring can have tabs which selectively engage a plurality of steps on the adaptor ring. Alternatively, the steps can be formed directly in the frame. Alternatively, first and second rings can be disposed between the frame and cover. The rings can have meshing steps.
U.S. Pat. Nos. 6,811,350 and 6,997,639 issued respectively on Nov. 2, 2004 and Feb. 16, 2006 to Nadasde, and the full disclosures of which are incorporated herein by reference, disclose an apparatus for adjusting the height and inclination of roadway and greenway appurtenances. The apparatus includes a rigid annular support ring mountable onto a rigid annular spacer ring sized so as to be mountable onto a manhole and a manhole frame mountable onto the support ring. The manhole frame is substantially frustoconically shaped. A rigid annular base flange may be mounted around a base end of the manhole frame. A plurality of threaded bores are formed in spaced array around the base flange. Rigid elongate threaded members are threadably mountable into the threaded bores so as to be selectively threadably adjustable in the threaded bores and so as to protrude downwardly from the base flange into engagement, beneath the manhole frame, with a top surface of the support ring when the manhole frame is mounted on the support ring. The threaded members are threadably adjustable in the threaded bores to elevate or to tilt the manhole frame relative to the support ring.
However, despite the above mentioned disclosures, there remains a need for an improved adjustable support structure for a utility access cover that may be used to adjust the height and inclination of a utility access opening.